Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual nação teve um cruzador de batalha com uma estimativa de 513?
 ###Tabelas: CREATE TABLE world_war_ii (world_war_ii_id AUTO_INCREMENT PRIMARY KEY, Estimate VARCHAR, Name VARCHAR, Nat. VARCHAR, Ship type VARCHAR, Where sunk VARCHAR, Date VARCHAR) CREATE TABLE list_of_the_most_populous_us_counties_sorted_according_to_the_mid-2011_official_estimate_by_the_uscb (list_of_the_most_populous_us_counties_sorted_according_to_the_mid-2011_official_estimate_by_the_uscb_id AUTO_INCREMENT PRIMARY KEY, Rank VARCHAR, County VARCHAR, State VARCHAR, Land area (km²) VARCHAR, Land area (mi²) VARCHAR, April 1, 2010 census VARCHAR, April 1, 2010 density (/km²) VARCHAR, April 1, 2010 density (/mi²) VARCHAR, July 1, 2010 official estimate VARCHAR, July 1, 2010 density (/km²) VARCHAR, July 1, 2010 density (/mi²) VARCHAR, July 1, 2011 official estimate VARCHAR, July 1, 2011 density (/km²) VARCHAR, July 1, 2011 density (/mi²) VARCHAR, Mid-2010 to mid-2011 change (Absolute) VARCHAR, Mid-2010 to mid-2011 change (%) VARCHAR, County seat or courthouse VARCHAR) CREATE TABLE stage_results (stage_results_id AUTO_INCREMENT PRIMARY KEY, Date VARCHAR, Course VARCHAR, Distance VARCHAR, Winner VARCHAR, Race Leader VARCHAR) CREATE TABLE electoral_results_1990–2008 (electoral_results_1990–2008_id AUTO_INCREMENT PRIMARY KEY, Election INT, candidates INT, seats won INT, votes INT, % of vote INT) CREATE TABLE junior_high_schools (junior_high_schools_id AUTO_INCREMENT PRIMARY KEY, School's name VARCHAR, School's namesake VARCHAR, Year opened VARCHAR, Principal VARCHAR, Mascot VARCHAR)  
SELECT Nat. FROM world_war_ii WHERE Ship type = battlecruiser AND Estimate = 513